Peruse the following website, which may be of help in furthering your research. In particular, the links near the bottom offer some good immersion resources such as radio.

"And how is it, bhikkhus, that by protecting oneself one protects others? By the pursuit, development, and cultivation of the four establishments of mindfulness. It is in such a way that by protecting oneself one protects others.

"And how is it, bhikkhus, that by protecting others one protects oneself? By patience, harmlessness, goodwill, and sympathy. It is in such a way that by protecting others one protects oneself.- Sedaka Sutta [SN 47.19]

It's not a method, but An Introduction to Spoken Sinhala by Professor W.S. Karunatillaka seems to be quite good. There is a PDF version on Scribit, but the scan quality is very low. It's good enough to get a sense of the book though.

BKh wrote:It's not a method, but An Introduction to Spoken Sinhala by Professor W.S. Karunatillaka seems to be quite good. There is a PDF version on Scribit, but the scan quality is very low. It's good enough to get a sense of the book though.

Do post back if you find anything else.

Thank you, that looks interesting indeed.

I found other things on the internet:On the wikipedia page for the Sinhala language, I found a link at the bottom for the USA Foreign Institute which has a basic course in Sinhala (3 rather large PDF documents).